Dave, I fail to understand how CV could be an issue, unless the DAC is too slow to react to input changes, and I find that hard to believe. If it is CV, Jeff should have the same problem I would think. Since my DAC is yet to be put into operation, I trying to think of a way to test response without a scope. I will have my DAC assembled this weekend (lasering a pc board for it now), but I'm still waiting on the new LD driver to arrive. Could you perhaps not be getting enough gray shade values min. Z to max?

I set my CV tolerance the same as my full depth of cut at .0255". I just assumed that if the shades would go from white to black abruptly, that would be max it would change all at once on the z axis. Dave, with your circuit can you have it go from 0-5V with 255 .0001" steps. Maybe the problem is even though it's not hooked to a stepper and you are using the C instead of Z, Mach still thinks it's making a big change in the g-code axis moves and effecting the detail.

Hi John, Jeff, Using a max depth of .060" with my machine should be getting me 240 steps or shades between 0 and 5 volts (it does if I single step jog in C while measuring the output). With this, and a cv distance tolerance of .010, I can see mach slowing down a bit when there are lots of transitions between dark and light. There's not as much slowdown if the max depth is .030, so it sort of sounds like the extra depth affects mach's calculations.

I plan on doing some more testing today - it's raining so the yard work is on hold Tried a few methods of locating the focus last night - the beam is really narrow so it's hard to tell. Burned a line on a piece of wood while varying the Z by an inch as the laser moved a fixed difference in Y, looked for the narrowest part of the line and used that to find the focal distance. It looks like there is quite a bit of height that doesn't seem to affect the width of the line. Think I'm pretty close now (4.25" in front of the case) but I'm going to look at that again today.

I'm also going to try changing the C axis steps/inch and acceleration to see if that helps.

the laser focal point takes 2 different steps or adjustments. One is the distance off your stock and the other is the focusing lens distance from the laser diode. To initially set it on mine was to bottom the Z axis all the way down and then I gave it a distance of .100" up as a starting point. Since my Z axis is 2-1 ratio, that was a .200" MDI move up. At that point since you have the same laser I do, that is exactly 3.00" off the table to the nose of the laser diode host. Not the heat sink. My piece of anodized aluminum is .75" thick (same thickness as my Birch ply) I moved up .75" actual distance or 1.5" MDI because of the 2-1 ratio. I rotated the focusing lens until the beam was the smallest on the black anodized aluminum.

Measuring the end of the focusing lens from the nose of the diode host, it's exactly .312". If your anywhere near 4.25" off your stock to the laser lens, then your way off based on my calibration method of focusing the lens. Try setting yours by making the nose of the diode host 3.00" off the table and make the focus lens stick out the host .312" and see what you get. The lens part that sticks out does not have any threads part way up. Maybe your lens is in upside down also. Of course you will have to move up the thickness of your stock from there to engrave.

Hi Jeff, Read your update, will have to peruse it over a couple of brews before I understand it. When you say host, you mean the front of the part that the lens housing screws into, right? And it's .312 from that to the front of the lens housing? Dave

yes you are correct. That same host face is 3.00" from the table when focused, so that makes the end of the lens housing 2.688" from the table, or the wood your engraving. My host should have the laser diode pressed into it in the same place as yours. I'm giving this as a reference and this should get you real close, but you may have to rotate the lens slightly one way or another to get the beam the smallest. It's a pain in the butt getting the lens the correct distance from the laser diode because it's a more sensitive adjustment then the distance off your material. The black anodized aluminum won't burn or reflect the beam when adjusting it so you can see when it is the smallest.

I want to add too, don't translate to English on this forum because it changes the wording around and that may be why you need some brews to understand.

OK, I'm back in business again I think. Had a very slight bind in the Y axis lead screw and a tiny bit of backlash too. I also decreased the C axis acceleration parameter to be more in agreement with the other axes. It also looks like the beam is narrower with the shorter 2.688" focal distance - with a stepover of .008", I can see separate raster lines if I look at it really close. Detail now is much better. For testing, I used some orange colored card stock - it's lots cheaper than birch for trouble shooting, but if the heat is turned up too far it cuts though in the darker areas

I feel like the lone ranger here. Is anyone else laser engraving any photos with a laser diode that can post some pictures also? Dave, how about you? Have you worked things out with your machine and circuit yet?

Haven't had much time to play lately - cleanup's been taking more than I thought. Downed tree was about a 60' pine, hope to have it all cut up tomorrow. Then I should get some playtime

Jeff, your pictures are looking really good. I still need to look for binds and/or slop in the X and Y axis leadscrews - sometimes I can see a repeating pattern where the raster line spacing is different.. It occurs about every tenth of an inch, the same as the leadscrew pitch.

John, I hope my diagram wasn't the cause of the burn-out. When I ordered the parts for mine, I ordered another complete set of chips just in case (don't ask why)

Actually, it was my stupid mistake, not your diagram. I put both counter chips in upside down. I'm using an old pair of glasses while new lenses are being made (yeh, poor excuse, I should know better). The second chip was protected because I had also overlooked installing a ground jumper to it. Parts have been shipped so I should be up with it soon. New dual analog driver arrived from Finland(?), so all pieces on hand except for the one counter chip.

I feel like the lone ranger here. Is anyone else laser engraving any photos with a laser diode that can post some pictures also? Dave, how about you? Have you worked things out with your machine and circuit yet?

Hi Jeff,

We don't mind you being the Lone Ranger, just keep posting the pictures - they are great.

Tweakie.Success consists of going from failure to failure without loss of enthusiasm.

Been out of town for a few days. Me and my wife made a trip to the Smokey Mountains in North Carolina last week. Stopped at a very cool motorcycle museum in Maggie Valley and took a few pictures. This one is a inline 4 cylinder Indian motorcycle. Doing one of a very old Harley right now and will post it later when it's finished.

I never thought about laser engraving leather. I wonder how responsive it would be to laser engrave shades on it. It looks like you TTL modulated your laser. How fast did you have your feedrate to get it to burn like that? I found that materials that are harder to burn are better to TTL modulate. It's either full power or no power. I have not gone back to sorting out what I did wrong the last time I tried to pulse my laser. That will be tomorrow.

I burn all leather at 20 ipm, and reduce power to about 50% (about 0.4 amps on my diode). I 'seal' the leather first with a wipe coat of Mequiar's leather cleaner/conditioner. Gcode is generated with Cut2D using a custom post for M10/M11 laser control.

Probably could burn faster, but this works so I haven't bothered to change it.

This leather is from a piece of reject Harley-Davidson seat leather that was given to me. It is about 1/8" thick - good quality.

If you try leather, be sure to vent your shop well - it don't smell too good. JohnI paint with a blue light beam.